Regulation of early gene expression in phage lambda is mediated by antitermination of transcription. However, the mechanism of transcription termination itself is not well understood. Towards a better understanding of the transcription termination antitermination mechanism, the Rho dependent t-R1 terminator along with its regulatory sequences was cloned onto a plasmid. Deletions of various lengths into the terminator segment were generated in vitro; DNA sequencing was then done to determine the deletion end points. After cloning these deletions onto an expression vector between a promoter and its structural gene, their effect on the expression of a distal gene is determined. Deletions that remove the terminator (or part of it) express the distal gene at higher levels than when transcription terminates at the terminator.